Polished rod insulation



Nov. 13, 1951 w. H. EDWARDS 2,

POLISHED ROD INSULATION Filed Nov. 10, 1949 Patented Nov. 13, 1951POIiISHED ROD INSULATION William H. Edwards, Houston, Tex., assignor toThe Texas Company, New York, N.- Y., a corporation of DelawareApplication November 10, 1949, Serial N0. 126,498

Claims. (Cl. 103--205) The present invention-relates to the pumpingof-wells, and more specifically is concerned with overcoming theelectrolytic corrosion ofsubsurface equipment used in a pumping welLforvoir,*not shown, at apoint below the surface of 'the 'ground, which isrepresented by the reference numeral l2.

' A'polished or sucker rod 14 extends vertically the production ofpetroleum, which results from 6 axially down the well casing itconnecting at its the flow of electrical surface energy through thelowerextremity with the piston of well pump, :sucker'or polished rod.not shown, which is disposed within the petro- The inventionparticularly contemplates the leum reservoir. disposition -of compactelectrical insulating Thesucker rod 14 is continually reciprocated meansbetween the =polished'rod and its source in an axial direction by anydriving and transof actuation at the polished rod cross. More spemissionmechanism, as for example, a pumping cifically, aninsulatingsleeve orbushing-is disjack not shown comprising a pivoted lever-or posedbetween-the polished rod of the pumping walking beam oscillated by adriving motor about assembly and-the hangeror polished rod cross, itsfulcrum or pivot point in'a vertical plane .andan insulating collar orwasher is caused to and suspending from its extremity, a pair ofseparate the upper surface of the hanger from driving cables or rods 16.Both cables [3, as the-polished rod clamp. 'As a result, a compact shownin Figure l, are connected as at IT with a and. relatively permanentmechanical connecpolished rod cross, yoke or hanger 18, whichactionjoins the polished rod to its driving instrucordingly iscontinually lifted and lowered mentalities, and simultaneously preventsthe flow through the desiredreciprocating path. vof electricity down thepolished rod. Mechanical connection between the polished A particularfeature of this arrangement rerod is and the polished rod cross I8 iseifected sides in the elimination of cumbersome insulatbypassing theextremity of the polished rod cening couplings by electrical insulatingmembers trally through an aperture or cylindrical paswhich remainessentially a fixed relationship if) sageway in the red cross or hanger8, and atwith respect to the parts which they electrically taching ahanger clamp 2| thereabove. The separate. As a result of the absence ofrelative hanger clamp 2| shown in the drawing is promovement, frictionalwear as well-as tensile vided with set screws 22 for rigid attachmentstressing of the insulating-members is essentially to the rod M althoughany other equivalent faseliminated. Therefore, continuous andpermateni-ng-or-locking means for interconnecting the nent insulation ofthe polished or sucker rod is clamp and the rod 14 against relativemovement continuously realized without the deterioration areobviouslycontemplated. which would be expected under the high me- -Inaccordance with the present invention, it'is chanical stresses and loadsusually encountered to be particularly'noted that the cylindrical pasinpumping assembliesof this character. sageway 20 is of substantiallygreater diameter Obviously-there is a complete suppression of thantherod 14 in order to accommodate an inelectrolytic corrosion, due toelectrical surface terposed electrical insulating sleeve, tube orcolcurrents passing through the sucker rod, curlar 23 which thereforeembraces the rod 14 and rents which otherwise reach substantial maglinesthe bore or aperture 20. r The sleeve 23 exnitude and are highlydestructive of the sucker 40 tends completely'throughthe aperture andprefrods, pump, casing, tubing and the like. erably' a short distancetherebeyond, as at 24, In order to describe the invention in greater topositively prevent electrical contact between detail, reference is hadto the attached drawing the d' a 't e h e wherein: As is particularlyshown in Figure 2, an insu- Figure 1 is 9, ertical elevation, partiallyin lating disc, 0011341, 01 washer 25 extends radially section, showingone embodiment thereof as apoutwardly from the upper portion of'thesleeve plied to a um ing et 1eu 311 23,-occupying the space between thelower sur- Figure 2 is a sectional detail view taken 'verface of theclamping cOHar 2| d the upper tically and centrally through theembodiment of face of the'polished rod cross l8. In the embodi- Figure lin the region where the sucker rod m t w Sleeve 23 an Wa er 26 arepasses through the hanger; and threadedly interen a ed as at 27.

Figure 3 is a sectional detail view taken on a y, e insulating he 2 extnds the lines 3-3 of Figure 2, radially outwardly beyond the margins ofthe In Figure 1, the numeral l0 represents a well collar to positivelyassure interruption of all eleccasing leading to a petroleum producingresertrical current flow between the parts but also to provide asubstantial and adequate contact surface for transmitting the mechanicalstresses encountered in actuation of the sucker rod l4.

Preferably, also, additional washers 28 and 29, formed of some materialof good structural properties such as steel, iron or the like, aredisposed respectively above and below the insulating washer todistribute these stresses uniformly through the insulating washer.

As above intimated, the interconnection between the tubular sleeve 23and the insulating washer 26 may take any conventional form. Forexample, these parts may be joined by any desired fastenings or may bemolded as an integral unit as a sleeve having a radial flange projectingfrom its upper extremity.

On the other hand, direct mechanical connection of these parts is notnecessary where other provision is made to permanently hold the sleeve23 in the position shown between the polished rod M and the hanger l8.For example, the sleeve may be held in position by clamps, setscrews orthe like joining it to either the hanger or the rod, or may be fastenedby any suitable means to either or both of the washers 28 and. 29.

As a result, however, of the arrangement of the tubular insulatingmember 23 in cooperation with the insulating flange 26, it .is obviousthat the polished rod remains electrically separate from its drivingmeans so that the usual current of relatively strong, solid, electricalinsulating material. However, it will be apparent from what has beensaid before that the substantial stresses normally encountered inpumping petroleum wells dictate the use of materials having substantialresistance to compressive stress and impact.

To this end, therefore, it is preferred to employ some relatively rigidinsualting material of high compressive strength, such as, for example,the following; polystyrene resins; vinyl acetate; pressed fiber; rubber;and the phenol-formaldehyde resins, for instance, Bakelite, or the linenbase molded product Micarta. In general, plastics of substantialcompressive strength and electrical insulating properties are suitable.

It is important to note that this structure adds subsantially nothing tothe bulk of the assembly by way of eliminating the electrolyticdestruction of subsurface equipment attributable to sucker rodconductors. In other words, this result is realized in a simple mannerwhich obviates the use of undesired, cumbersome insulating couplingswhich would impair the vital strength and permanence of the assembly.

Obviously, many other modifications and variations of the invention ashereinbefore set forth may be made without departing from the spirit andscope thereof, and only such limitations should be imposed as areindicated in the appended claims.

I claim:

l. In a well pumping apparatus in which a well pump is actuated by astring of polished rods suspended in the well from a verticallyreciprocating driving mechanism at the surface, said mechanism includinga cross member and means for suspending the cross member from saidmechanism, the polished rod extending vertically through an aperture insaid cross member and having a clamp afiixed to the rod above the crossmember, the improvement which comprises means for electricallyinsulating said polished rod from said cross member comprising a sleeveembracingthe polished rod and disposed within the said aperture of thecross member, and a projecting collar extended radially outwardly fromthe upper extremity of the sleeve and separating the upper surface ofsaid cross member from said polished rod, said sleeve and collar beingformed of electrically insulating material.

2. The combination called for in claim 1 wherein said insulating sleeveis attached to said insulating collar, thereby continuously locating thesleeve within the aperture in said polished rod cross member.

3. Means for electrically insulating the polished rod from a positivelyreciprocated polished rod cross member of a petroleum pumping well,wherein said polished rod extends vertically and axially of a petroleumwell casing from a subsurface reservoir to the surface of said well,said polished rod passing through an opening in said polished rod crossmember in the vicinity of its upper extremity and being provided abovesaid aperture with a rigidly attached polished rod clamp projecting overthe upper surface of the cross member to thereby suspend the polishedrod, said insulating means comprising a cylindrical sleeve having aninternal and an external diameter permitting said sleeve to fitcoaxially about the polished rod and within the said aperture in saidpolished rod cross member, and an annular collar interengageable withthe upper extremity of said sleeve and extending radially outwardlytherefrom a substantial distance to lie 1 between said polished rodclamp and the upper surface of said cross member, said sleeve and collarbeing formed of electrically insulating material.

4; The apparatus according to claim 3 wherein the upper extremity ofsaid sleeve is provided with a screw thread on its outer surface andwherein said collar is provided with a mating thread, permitting thesleeve and collar to be threadedly interengaged against relative axialmovement.

5. The apparatus according to claim 3, having in combination therewith apair of rigid metallic washers having annular faces substantiallycoextensive with the annular surfaces of said collar and adapted tooppositely engage said faces to distribute compressive stress throughthe collar.

WILLIAM H. EDWARDS.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,038,527 Eaton Apr. 28, 19362,230,029 Eaton Jan. 28, 1941 2,237,303 Calhoun Apr. 8, 1941

